Modern aircraft engines, such as the gas powered turbine engines incorporated in commercial aircraft, operate at extremely high temperatures. As a result of the high temperatures, components within the engine are cooled using a cooling flow from a lower temperature working fluid, such as air. In order to cool the coolant, high temperature/high pressure heat exchangers are utilized. In such a heat exchanger, hot coolant is passed through one or more passages, and a cross flow of a cooler fluid, such as lower temperature flow, is passed across the outside of the passage. Convective cooling transfers heat from the fluid in the passage to the cross flow, and the cross flow draws the heat away from the coolant in the passage.
Current high temperature/high pressure heat exchangers, such as those required by cooled cooling air aircraft systems, are subjected to severe design constraints. To meet the design constraints, the heat exchangers typically use discrete drawn tubes that create passages for the high pressure and high temperature flow of coolant. While this solution is viable in some systems, the use of drawn tubing can limit the materials that can be used to construct the heat exchanger and can limit the use of secondary, or augmenting, heat transfer features within the heat exchanger.